New 3,5-dimethylpyrazole copper(II) compounds with a variety of hydrogen bonds, synthesized by using a dehydrating agent: Synthesis, characterization, structures and intermolecular interactions

Six new mononuclear-based compounds have been synthesized with formula [Cu(Hdmpz)4(BF4)2] (1), [Cu(Hdmpz)4(ClO4)2] (2), [Cu(Hdmpz)4(CF3SO3)2] (3), [Cu(Hdmpz)4(NO3)2] (4), [Cu(Hdmpz)3(NO3)2] (5), [Cu(Hdmpz)4(H2O)](CF3SO3)2 (6), in which Hdmpz = 3,5-dimethylpyrazole. In addition a complete 3-D structure determination for five of these compounds was performed. All compounds have also been characterized by elemental analysis, IR, ligand field and EPR spectroscopy. Special attention is given to the differences in hydrogen bonding properties, which do vary with the Cu(II) chromophore and with varying anions; The used anions have different effects on the intermolecular hydrogen bonding, which is also reflected in the weak exchange couplings, as deduced from the EPR line widths.